I remember Sesame Street had an episode on the death of Mr. Hooper.
Any others?
Sesame Street again:
They Dealt with a Hurricane destroying Big Birds home. (Pre-Katrina)
They Dealt with 9/11 by visiting a fire department and learning about fires.
They Dealt with one of the human characters having a baby.
Arthur has dealt with Racism and prejudice in a few episodes.
These are ones I am aware of.
Jim
A special episode of Blue’s Clues dealt with Joe going away to college, and talked about ways we can stay connected to loved ones who have to leave. The same show also dealt with sibling rivalry when Mr. Salt and Mrs. Pepper had a baby, and Paprika was afraid they wouldn’t love her as much any more.
The '90s X-Men cartoon on FOX got pretty deep and topical for a kid’s action cartoon – racism, wanting to be something that you’re not, accepting yourself for who you are, etc. There was even one episode where Storm and Wolverine go into a restaurant holding hands, and the owner tells them he doesn’t serve mixed-race couples.
Mr. Rogers had a show where he dealt with death when one of the goldfish went belly up. I also vaguely recall that there might have been an “Arms Race” episode where King Friday wanted a new weapon (what was he going to do? Nuke Sesame Street?) I never actually saw either of those episodes, just heard about them in the news.
Pepper Ann had a whole episode about death. From what I remember, Pepper Ann spends the whole episode worrying and wondering what happens after death, and basically comes to the conclusion that nobody really knows, but you shouldn’t worry too much about it.
Our local Sesame franchise “Takalani Sesame” has an HIV+ kid muppet, and the disease is dealt with sometimes, when relevant, but mostly she’s just another character.